A rip current is a strong channel of water moving away from the shore. Rip currents typically form along the beach at breaks in the offshore underwater sandbar, but they can also form near structures such as jetties and piers.
Best disk wiping tools-the tool depends on the task. Disk wiping is a non-destructive way of permanently removing data very different from data destruction, either physical or using a degaussing system that does the same job at the expense of destroying the drive itself.
The cheapest way to tackle a pile of hard drives is to wipe them with a software eraser. I warn you though, it's not quick, and it won't work on defective disks. My tool of choice for wiping drives is Darik's Boot And Nuke. It's free and does an excellent job of wiping drives clean. To use it you'll need to create a wipe CD or DVD, and then hook up the drives you want to wipe to a PC and run the software. Be careful not to inadvertently wipe a drive containing data you need, because that will make your life suck.